1. Field of the Invention
The present invention generally relates to a sheetless backlight module and a design of a light guide plate for the sheetless backlight module. Particularly, the present invention relates to a sheetless backlight module having a wider range of light-exiting angle and a light guide plate thereof.
2. Description of the Prior Art
Liquid Crystal Display (LCD) devices are extensively used in a variety of electrical devices such as computers, televisions, and mobile phones, wherein a light guide plate is used in a backlight module of the LCD device and is an essential element related to the light utilization efficiency. In addition to the light guidance and the control of exiting-light, the light guide plate is designed to elevate luminance and light uniformity, therefore improving the light utilization efficiency and optimizing the visual quality. In addition, accompanying the technology improvement in the display device industry as well as the user demands, display devices are getting smaller and lighter. According, the interior components/elements of the display devices are required to have the same or even better function under the limited volume or space.
As FIG. 1A shows, the sheetless backlight module 1′ has less cost of production due to no optical films such as diffuser or prism films used and therefore is lighter and smaller than the conventional backlight module. On the other hand, since the sheetless backlight module does not use the diffuser film, light exiting thereof is more direct and the light energy is more centralized. However, the sheetless backlight module 1′ has defects of hot spot and light ray which are concerned in visual quality. In addition, along with the more-direct light-exiting, the light energy does not disperse enough and the view angle of the backlight module 1′ is too small as shown in FIG. 1B.